Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

sendler · 06-27-2013, 12:32 AM

An airfoil or tear drop is the most efficient shape. Concessions must be made to make it practical.
.
One simple design trait I see in modern race motorcycles is that the bodywork between the wheels is designed to be just shy of dragging the ground under full compression. This smooths the flow, which wouldn't be an issue with a full streamliner, but also makes the Center of Pressure from the side as low as possible. Having the side CoP lower than the CG of the role axis aids in getting the best self correction in side winds by pushing the bottom of the bike more than the top to lean it into the wind. Trail also takes the side load and through gyroscopic precession leans the bike into the wind as the trail also countersteers the front wheel away from the wind to increase the lean further. You see this in dramatic fashion in the 50mph side wind test of the Peraves. It was blown off line 3 feet but leaned into the wind and automatically recovered in one oscillation.
.
A "symmetrical wing with an angle of attack" is created by a bike moving forward at a significantly higher speed than the side wind. Venting the resulting pressure differential also helps reduce the (side) lift that is acting on the bike as Craig found out when he added doors to his streamliner and then had to take the back off when he found it was worse in side winds.
.
Nose overhang is bad
.
The human powered vehicle has way too much nose overhang which makes them very difficult to ride in side winds of more than a few mph.
.
A pro rider can do 450 watts for an hour and 2000 watts for 10 seconds.

06-27-2013, 12:32 AM	#5 (permalink)
sendler Master EcoModder Join Date: May 2011 Location: Syracuse, NY USA Posts: 2,935 Honda CBR250R FI Single - '11 Honda CBR250R 90 day: 105.14 mpg (US) 2001 Honda Insight stick - '01 Honda Insight manual 90 day: 60.68 mpg (US) 2009 Honda Fit auto - '09 Honda Fit Auto 90 day: 38.51 mpg (US) PCX153 - '13 Honda PCX150 90 day: 104.48 mpg (US) 2015 Yamaha R3 - '15 Yamaha R3 90 day: 80.94 mpg (US) Ninja650 - '19 Kawasaki Ninja 650 90 day: 72.57 mpg (US) Thanks: 326 Thanked 1,315 Times in 968 Posts	An airfoil or tear drop is the most efficient shape. Concessions must be made to make it practical. . One simple design trait I see in modern race motorcycles is that the bodywork between the wheels is designed to be just shy of dragging the ground under full compression. This smooths the flow, which wouldn't be an issue with a full streamliner, but also makes the Center of Pressure from the side as low as possible. Having the side CoP lower than the CG of the role axis aids in getting the best self correction in side winds by pushing the bottom of the bike more than the top to lean it into the wind. Trail also takes the side load and through gyroscopic precession leans the bike into the wind as the trail also countersteers the front wheel away from the wind to increase the lean further. You see this in dramatic fashion in the 50mph side wind test of the Peraves. It was blown off line 3 feet but leaned into the wind and automatically recovered in one oscillation. . A "symmetrical wing with an angle of attack" is created by a bike moving forward at a significantly higher speed than the side wind. Venting the resulting pressure differential also helps reduce the (side) lift that is acting on the bike as Craig found out when he added doors to his streamliner and then had to take the back off when he found it was worse in side winds. . Nose overhang is bad . The human powered vehicle has way too much nose overhang which makes them very difficult to ride in side winds of more than a few mph. . A pro rider can do 450 watts for an hour and 2000 watts for 10 seconds.